When performing an apheresis procedure, a single-use kit is primed prior to commencement of the procedure to remove air from the kit that might otherwise be returned to the patient/donor. This initial priming is typically done with a saline solution or a mixture of saline and anticoagulant, and at least a portion of the saline prime is typically returned to the patient/donor at the commencement of the procedure. However, when the extracorporeal blood path volume of the single-use kit is large relative to the volume of blood of the patient (for example, greater than about 10-15% of the patient's total blood volume, as may occur for pediatric or small-sized patients), or if the patient is anemic or hemodynamically unstable, the return of the saline prime at the commencement of the apheresis procedure could be detrimental to the patient's well-being.
In such instances, and more particularly in a therapeutic apheresis procedure, it may be desirable to perform a “blood prime” in which whole blood or normalized whole blood (packed red blood cells reconstituted with saline and/or albumin) is used to prime the system subsequent to the initial priming with saline so that, at the commencement of the therapeutic procedure, patient-compatible blood is returned to the patient simultaneously with blood being withdrawn from the patient, thus maintaining a generally constant total blood volume and red blood cell mass and/or volume for the patient.
In typical apheresis procedures, blood primes are performed manually by the operator with reference to an instruction sheet. Patients for whom a blood prime may be indicated are generally much more sensitive to minor shifts in their fluid balance and blood volume, and the operator must be alert to this. If the operator is inexperienced with blood priming, additional stress may result from performing the blood prime, and the operator's attention may be diverted from the monitoring of the patient. By way of the present disclosure, an automated blood prime method is provided.